The objectives of the proposed research are to isolate and purify from post mortem human hepatitis B livers various classes of serologically specific particles especially those which contain nucleic acid. Liver homogenates will be chromatographed on calcium phosphate (brushite) columns. Fractions containing serologically specific reactants will be further purified by equilibrium density gradient and rate Zonal sedimentation. Purified populations of virus-like particles will be examined morphologically for their content and type of nucleic acid. The physical and chemical properties of nucleic acid extracted from given species of particles will be characterized. The potential of the nucleic acid containing particles for infectivity will be tested in tissue cultures.